Effect of sodium meta-bisulfite chemical pretreatment and drying temperatures on qualitative characteristics of barberry fruit

This experiment was conducted in order to evaluate the effect of sodium meta-bisulfite chemical pretreatment and different temperatures of hot air on quality of dried barberry fruits as split-plot in time, with sodium meta-bisulfite (Na2S2O5) in 4 levels (0, 1, 2 and 4%), drying temperatures in 3 levels (50, 60 and 70ºC) and storage time in 6 levels of fresh fruit (harvest time) and dried fruits (0, 20, 40, 60 and 80 days after drying). Fruit moisture content was reduced up to 13±1%. Na2S2O5 significantly influenced most characters including antioxidant activity (AA), and its 2% concentration increased color indices. Simple effect of drying temperature was significant on pH, L (brightness), ΔE (total color change) and BI (browning index), and any increment of temperature was led to higher BI, although no effect was observed on AA and ANT (anthocyanin). Simple effect of storage time was significant on all variables, and TSS was increased with time, although L decreased. Interaction between chemical pre-treatment and temperature also significantly influenced pH, TA and TSS. It is concluded that although low drying temperatures are needed to maintain quality of dried barberry fruit, however, parallel application of chemical pre-treatment with lower drying temperatures lead to improve color indices of dried barberry fruit, although further experiments are required.